This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled METHOD FOR SENDING IMAGE SIGNAL earlier filed in the Korean Industrial Property Office on Jul. 13th1999, and there duly assigned Serial No. 99-28202.
1. Field of the Invention
The present invention relates to a method and apparatus for transmitting a video signal, and more particularly, to a method and apparatus for transmitting a video signal by processing a video signal from a computer and inputting the processed signal to a cathode ray tube (CRT) monitor.
2. Description of the Related Art
In a typical computer, a graphic controlling unit controls a video random access memory (RAM) according to a control signal, an address signal and a data signal from a central processing unit (CPU) to generate a parallel digital video signal. The parallel digital video signal is converted to an analog video signal and then is transmitted to a cathode ray tube (CRT) monitor.
Referring to FIG. 1, a video card of a conventional computer 100 includes a graphic controller 11, a video random access memory (RAM) 12, a clock pulse generator 13 and a digital-to-analog converter (DAC) 14. The graphic controller 11 reads or writes data from or to an input address (ADR) area of the video random access memory (RAM) 12 by means of a read/write signal (R/W) according to a control signal (CTR) output from the central processing unit (CPU) 10 of the computer 100. The graphic controller 11 and the digital-to-analog converter (DAC) 14 operate according to a clock pulse signal (CLK) output from the clock pulse generator 13.
The graphic controller 11 processes data output from the video random access memory (RAM) 12 to generate a parallel digital red video signal RP, a parallel digital green video signal GP, a parallel digital blue video signal BP, a horizontal sync signal HSYNC, a vertical sync signal VSYNC and a data enable signal DE.
The digital-to-analog converter (DAC) 14 processes the parallel digital signals output from the graphic controller 11 to generate an analog red video signal RA, an analog green video signal GA, an analog blue video signal BA, and an analog synthesized sync signal SYNCA. The analog signals output from the digital-to-analog converter (DAC) 14 are transmitted to a monitor 110 via a metal cable 15.
An amplifier 16 of the monitor 110 amplifies the received analog video signals RA, GA, and BA and inputs the amplified signals RA, GA, and BA to a cathode ray tube (CRT) driver 18 of monitor 110. Also, a synchronization controller 17 of monitor 110 controls the received analog synthesized sync signal SYNCA to input this controlled signal to the cathode ray tube (CRT) driver 18.
According to the conventional transmission method, the parallel digital video signals are transmitted as converted analog signals. Thus, noise externally generated affects the transmission of the analog signals so that the video signals are easily distorted during the transmission period.
To solve the above problem, it is an objective of the present invention to provide a method and apparatus for transmitting a video signal from a computer to a cathode ray tube monitor by processing the video signal so that the rate of distortion of the transmitted video signal can be reduced.
Accordingly, to achieve the above objective and other objectives of the present invention, there is provided a method of and apparatus for transmitting parallel digital video signals output from a graphic controller of a computer to a driver of a cathode ray tube monitor, transmission being achieved by converting the parallel digital video signals to serial digital video signals, transmitting the converted serial digital video signals to the cathode ray tube monitor via a cable, converting the transmitted serial digital video signals to serial analog video signals, and inputting the converted serial analog video signals to the driver of the cathode ray tube monitor.